1. Field of the Invention
The present invention relates to a grommet to be mounted on the wire harness for an automotive vehicle for fitting to a through hole of a vehicle body panel, and to a method for mounting the grommet onto a panel.
2. Discussion of Background Information
Conventionally, in laying the wire harness from the engine compartment into a passenger compartment, a grommet 1 of rubber or elastomer has been provided on the wire harness W/H, as shown in FIG. 4 and FIG. 5. The wire harness W/H is provided with the grommet 1 and is inserted into the through hole 3 of a vehicle body panel 2 separating the engine compartment (X) and the passenger compartment (Y). The grommet 1 is inserted into the periphery of the through hole 3, and is passed from the engine compartment side to the passenger compartment side through the through hole 3 and is positioned therein to prevent water or dust from entering into the passenger compartment from the engine compartment side
The grommet 1 has a small diameter tubular part 1a which tightly engages around the wire harness W/H, and an enlarged diameter tubular part 1b which continues in a conical shape from an end of the small diameter tubular part 1a. A recess 1c for engaging the vehicle body is provided on the outer peripheral surface of the enlarged diameter tubular part 1b. The recess 1c is engaged in the through hole 3 of the vehicle body panel 2 to fit the grommet 1 to the vehicle body panel 2. In order to increase the engaging force at the time of the mounting, the part provided with the recess 1c for engagement with the vehicle body is formed into thick wall, and the recess 1c is formed to be deep.
The grommet 1 has conventionally been installed, as shown in FIG. 5, by being inserted from the engine compartment (X) to the passenger compartment (Y) through the through hole 3 from the enlarged diameter tubular part 1b side. To this end, the entire grommet 1 is pushed into the passenger compartment (Y), while inwardly deforming the outer peripheral parts having the recess 1c, which parts are larger in diameter than the inner diameter of the through hole 3. Thereafter, the wire harness W/H is pulled from the engine compartment (X) side, and the recess 1c is engaged in the through hole 3 to mount the grommet 1 to the vehicle body panel 2. In other words, by two motions of first pushing the grommet into the passenger compartment (Y) from the engine compartment (X), followed by pulling the grommet back into the engine compartment, mounting of the grommet 1 to the vehicle body panel 2 is performed. The reason the grommet is installed by first pushing in, and then pulling back again to have the recess 1c engage with the vehicle body panel 2, is because if pushing of the grommet in is made by inserting the surrounding wall 1e of large projection amount into the through hole, engagement of the periphery of the through hole 3 in the recess 1c between the peripheral wall 1f of small projection amount cannot be assured by good feel.
Recently, as a consequence of the sharp increase in the number of parts to be mounted in an automobile, often many parts are arranged on both sides of the vehicle body panel 2 near the position where the grommet 1 is mounted. As described above, in mounting the grommet 1 onto a vehicle body panel 2, first, the entire grommet 1 is pushed into the passenger compartment from the engine compartment side, in which case it has become difficult to provide sufficient space for receiving the grommet which has been pushed into the passenger compartment. In addition, since it has been the practice to pull the grommet back into the engine compartment, there has become less working space for pulling the wire harness W/H and grommet into the engine room side, even on the engine compartment side.
If, instead of the two motions of pushing and pulling as described above, a small diameter tubular part 1a of the grommet 1 is pushed into the through hole 3 as an insertion side from the engine compartment side and the recess 1c is engaged with the periphery of the through hole 3 as shown in FIG. 6, the grommet 1 can be mounted to the vehicle body panel 2 by a single pushing motion. In such a case, however, because the small diameter tubular part side A of the recess 1c is formed into a thick wall, intensive resistive forces act when passing the grommet through the through hole 3, and the insertion of the grommet cannot be easily performed. Furthermore, with the above method, as shown in FIG. 7, there is a tendency for a gap C to be formed between the wall surface 1c-1 on the front side of the recess 1c and the panel 2, which results in inferior water stopping performance.
The present invention has been made in the light of the problems described above, and an object of the present invention is to provide a grommet having a construction for mounting the grommet onto the vehicle body panel by a single motion of pushing in from the engine compartment side, and to a method for mounting the grommet.
In order to achieve the above object, the present invention provides a grommet formed, for example, of rubber or elastomer, and having a small diameter tubular part to tightly receive a wire harness inserted therein. An enlarged diameter part continues from an end of the small diameter tubular part into a conical tubular shape, and an annular vehicle body engaging recess is provided on the outer peripheral face of the enlarged diameter tubular part. The wall thickness of the enlarged diameter tubular part is configured to be approximately the same from the position of continuation with the small diameter tubular part to a bottom end of a first side wall of the vehicle body engaging recess. The first side wall is formed to have a turned-back portion from a tip of an inclined part that continues from the conical tubular shape to the bottom end to provide a space at the back face of the first side wall, and an inclined part having an inclination is formed from a bottom face of the recess extending toward a second side wall of the recess. Additionally, a thick wall portion forms a second side wall and a front end face of the enlarged diameter tubular part, and a lip projects from the second side wall toward the first side wall.
As described above, by forming the turned-back portion of the first side wall of the small diameter tubular part of the recess for engaging the vehicle body, a gap is provided on the back face of the first side wall. Thus, due to the thin wall of the first side wall, upon exertion an external force to the first side wall, the side wall is readily deformed, and upon release of the external force the first side wall is restored to its original condition and the first side wall projects outwardly. Accordingly, when the first side wall is passed through the through hole of the panel, the first side wall is pressed by the inner peripheral face of the through hole (in case the through hole is provided with a burring, by the burring) to inwardly deform the diameter, and the first side wall easily passes through the through hole. Also, because the first side wall is formed to have a thin wall and is inclined after passing through the through hole, the first side wall is pressed into tight contact with the panel toward the second side wall side, and the lip projecting from the second side wall side and the panel can be brought into tight contact with each other.
When the outermost end of the lip projects toward the small diameter tube side farther than the outer end position of the first sidewall, tight contact force between the lip and the panel can be increased, and improvement of the water stopping performance can be expected.
The grommet, under the condition of being fixedly mounted to the wire harness, is inserted into the through hole with burring of the vehicle body from the small diameter tube side, the first side wall is pressed by the burring so that the diameter is inwardly deformed to pass through the through hole of the vehicle body panel. After the first side wall is passed through the through hole, the first side wall is restored to its original condition, so that the periphery of the through hole of the vehicle body panel is engaged with the recess between the first side wall and the second side wall, by simply being pressed in. Thus, the grommet is mounted to the vehicle body panel by only a single motion.
Consequently, the grommet is mounted to the vehicle body panel by a single motion of pressing into the through hole with burring provided on the vehicle panel from the engine compartment side to the passenger compartment side. Accordingly, even when there is no space in either the engine compartment side or the passenger compartment side, the work of mounting the grommet to the vehicle body panel can be performed without any difficulties.